1. Field of the Invention
The present invention relates to novel dipeptide derivatives and the salts thereof, sweetening agents comprising any of them as the active ingredient, and the products to have been sweetened, which comprise any of the sweetening agents.
2. Description of the Related Art
1. Actual State of the Sweetening Agents
With advanced eating habits in these days, obesity to be caused by over-intake of sugar and its related various diseases have become problematic. Therefore, the development of low-calorie sweetening agents that replace sugar has been desired. At present, aspartame is one popular sweetening agent which is excellent in safety and quality of sweetness. However, it involves a probleme in its stability. Recently, it has been found that the alkylation of the amino group of dipeptide derivatives such as aspartame is effective in greatly increasing the degree of sweetness of the resulting derivatives, for example, as in French Patent Nos. 2,697,844 and 2,719,592, and Japanese Patent Kouhyou Publication JP-A-8-503206. However, those alkylated dipeptide derivatives are still unsatisfactory in their stability.
2. Object of the Invention
In the course of the present invention, such above problems have been also found.
The object of the present invention is to provide novel dipeptide derivatives and their salts using .alpha.-alkyl-amino acid components, which are highly stable, highly safe and can be easily obtained, and also to provide low-calorie sweetening agents containing them as the active ingredients.